diff --git a/core/src/magic.sld b/core/src/magic.sld
index 9fe9e3d..96ce27c 100644
--- a/core/src/magic.sld
+++ b/core/src/magic.sld
@@ -56,6 +56,10 @@
      (define references-filtered (list-copy references))
      (define self-references (member path references-filtered string=?))
      (when self-references
+       ; It turns out these are broken in both Nix and Lix.
+       ; Also, I now don't have to implement the _second_ type of modulo
+       ; hash in Scheme, so that's a win for me.
+       (error "Refusing to import self-referenced CA path into the store.")
        (if (null? (cdr self-references))
          (set! references-filtered '())
          (begin